微波水熱合成多孔性二氧化鈦及鈦酸鋇奈米粉體

二氧化鈦是一種高用途的半導體，可應用在光催化、太陽能電池和一般工業上的半導體產業。鈦酸鋇是一種高介電常數的陶瓷粉體，主要為積層及陶瓷電容器之關鍵原材料。在二氧化鈦方面，製作成中孔洞主要是提高本身粉體的表面積；而在鈦酸鋇部分，製作成中孔洞，再藉由燒結使得粉體緻密，進而降低本身BT陶瓷晶粒的粒子大小。本研究主題為利用微波水熱快速合成多孔洞結晶性二氧化鈦及利用sol-gel方式合成多孔洞結晶性鈦酸鋇粉體。利用自組性微胞水解縮合製作中孔洞二氧化鈦結晶粒子大小約100-300nm並且其蟲洞大小約為3-5nm。微波水熱可以形成好的結晶相並具有高表面積，而表面積可高達243~622 m2/g，而鍛燒400°C/3h則會大大降低表面積。微波水熱也證實了可以快速形成結晶相並且有良好的光催化活性的中孔洞TiO2。另一方面，利用自組性微胞水解縮合製作中孔洞鈦酸鋇結晶粒子大小約100-300nm。鍛燒中孔洞的鈦酸鋇是值得研究的。中孔洞粉體表面積經鍛燒400 °C移除界面活性劑後，其表面積約53~108 m2/g。以Ba(OH)2為起始物合成的BaTiO3有大孔洞並具高表面積。而加入醋酸也有效的增加表面積。熱處理造成孔洞收縮，並且在燒結900 ~1000 °C 一個小時後，晶粒約為155 ~ 330nm，適用於現今的多層陶瓷電容器之薄層後< 2µm之要求。

關鍵字

二氧化鈦；中孔洞；鈦酸鋇

並列摘要

Titania is a highly useful semiconductor which is used for photocatalytsis, solar cells and industry of semiconductor. Barium titanate is a kind of ceramic powder with high dielectric constant, which is high volumetric efficiency, and the main material for Multi-Layer Ceramic Capacitor. For Titanua, mesoporous structure increases the surface areas. For Barium Titanate, mesoporous structure results in small grain size of BT ceramic after sintering. This study is to rapidly forming mesoporous crystalline TiO2 photocatalysts using microwave hydrothermal process and forming mesoporous crystalline BaTiO3 using sol-gel process. Mesoporous titanate crystalline nanopowders having 100-300 nanometer size with worm hole-like pore size 3-5 nm were prepared by hydration and condensation of titanium tetra-isopropoxide (TTIP) in the presence of organic surfactant, tetradecylamine, which was used as a self-assembly micelle. A novel microwave hydrothermal process was carried out in order to harvest crystallized anatase nanoparticles with high surface area. Mesoporous worm hole-like and crystalline powders with surface areas 243~622 m2/g was obtained. It is shown that crystallization by calcination at 400°C/3h inevitably reduced the surface area while microwave hydrothermal process demonstrated a rapid formation of crystalline mesoporous titanate nanopowders with high surface area and excellent photocatalytic effects. On the other hand, mesoporous barium titanate powders having a 100- to 300-nm size were prepared by hydration and condensation of titanium tetra-isopropoxide and barium precursors in the presence of an organic surfactant, tetradecylamine, which was used as a self-assembly micelle. The processing and sintering of these mesoporous barium titanate powders has been investigated. Mesoporous wormhole-like powders with surface areas around 53~108 m2/g could be obtained after removing the micelle organics by calcination at 400 °C for 3 h. Powders derived using barium hydroxide were found to form a larger pore size and a higher surface area. The addition of acetic acid was also effective in increasing the surface area. A formation mechanism for the mesoporous structure is depicted. Heat treatment caused the mesoporous spheres to shrink, and 155- ~330-nm grain sizes were readily obtained after pressureless sintering at 900 ~1000 °C for 1 h in air, which is suitable for requirement of thin layer < 2 µm in current MLCC technology.

並列關鍵字

BaTiO3 ； TiO2 ； mesoporous

參考文獻

[1]Frank Caruso., “Nanoengineering of Particle Surfaces.’’ Adv. Mater.13 (2001) 11-21

[2] R.Davies, et.al., “Engineered Particle Surfaces.’’ Adv. Mater. 10(1998) 1264-1270

[5] Hayashi S, Kon R, Ichiyama Y, et al., “Evidence for surface-enhanced Raman scattering on nonmetallic surfaces: Copper phthalocyanine molecules on GaP small particles .’’ Phys. Rev. Lett. 60(1988) 1085-1088

[6] Rossetti R, hull R, Gibson J M, et al., “Excited electronic states and optical spectra of ZnS and CdS crystallites in the ≊15 to 50 Å size range: Evolution from molecular to bulk semiconducting properties. ’’ J. Chem.Phys. 82(1985) 552-559

[8] Chen J Y, Gao L, Huang J H. “Preparation of nanosized titania powder via the controlled hydrolysis of titanium alkoxide. ’’ J.Mater. Sci.31(1996)3497-3500

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微波水熱合成多孔性二氧化鈦及鈦酸鋇奈米粉體

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